|
|
Untersuchte Arbeit: Seite: 37, Zeilen: 13-20 |
Quelle: Evonik 2009 Seite(n): 4, Zeilen: l.col.: 19 ff. |
---|---|
Siloxane (ºSi-O-Siº) and silanol (ºSi-OH) groups are situated on the surface of fumed silica particles. This latter type (i.e. silanol) of functional groups in particular is responsible for the hydrophilic behavior of non-after treated fumed silica types. Figure 3.4 shows the surface groups of hydrophilic AEROSIL fumed silica. AEROSIL fumed silica can be surface-modified by reacting the silanol groups with suitable compounds such as silanes. For example Aerosil R972, is produced by reacting hydrophilic silica with dimethylchlorosilane as shown in Figure 3.5 .this product exhibits chemically bound dimethyl silyl groups on its surface and can no longer be wetted with water – in other words, it is hydrophobic. | Siloxane and silanol groups are situated on the surface of AEROSIL® particles. This latter type of functional group in particular is responsible for the hydrophilic behavior of non-aftertreated AEROSIL® types. Figure 1 shows the surface groups of hydrophilic AEROSIL® fumed silica. For basic details and applications of AEROSIL® fumed silica, see issue number 11 of the pigments publication series [1].
AEROSIL® fumed silica can be surface-modified by reacting the silanol groups with suitable compounds such as silanes. AEROSIL® R 972 is obtained by reaction with dimethyl-dichlorosilane, for example; this product exhibits chemically bound dimethyl silyl groups on its surface and can no longer be wetted with water – in other words, it is hydrophobic. (1) Technical Bulletin Fine Particles, No. 11, Basic Characteristics of AEROSIL® fumed silica, 6th edition 2003, Degussa AG, D-40402 Düsseldorf, Germany |
The source is not mentioned. |
|